Sampling molten metal baths

ABSTRACT

The concentration of a constituent in a molten bath is quickly determined by obtaining a sample in a reactor to form gaseous product related to the constituent, removing the gaseous product to an analytical zone and analyzing. For example, in determining the active oxygen content of a molten steel bath, a sample is obtained in a chamber where it contacts carbon whereby active oxygen is converted to carbon monoxide which is swept in a stream of carrier gas to a gas chromatographic station.

United States Patent [191' Miller et al.

[ 1 SAMPLING MOLTEN METAL BATHS [75] v lnventors: Gerald G. Miller,Toronto, Ohio;

Rox L. Zickefoose, Weirton, W. Va.

[73] Assignee: National Steel Corporation,

Pittsburgh, Pa.

[22] Filed: Nov. 3, 1972 [21] Appl. No.: 303,503

[52] US. Cl 73/19, 23/230 PC, 23/230 C, 23/253 PC, 23/254 R, 73/231,73/4254 R,

[51] Int. Cl. G0ln 1/10, G0ln 31/08 [58] Field of Search... 73/19, 23.1,425.4 R, DIG. 9; 23/230 PC, 253 PC, 232 C, 254 R, 254 E;

[56] References Cited UNITED STATES PATENTS 3,427,863 2/1969 Schultz73/19 X June 28, 1974 3,656,350 4/1972 Collins 73/4254 R PrimaryExaminerRichard C. Queisser Assistant Examiner-Stephen A. KreitmanAttorney, Agent, or FirmShanley & O'Neil [5 7] ABSTRACT Theconcentration of a constituent in a molten bath is quickly determined byobtaining a sample in a reactor to form gaseous product related to theconstituent, removing the gaseous product to an analytical zone andanalyzing. For example, in determining the active oxygen content of amolten steel bath, a sample is obtained in a chamber where it contactscarbon whereby active oxygen is converted to carbon monoxide which isswept in a stream of carrier gas to a gas chromatographic station. A

25 Claims, 5 Drawing Figures BACKGROUND OF THE INVENTION This inventionrelates to system and method for determining the concentration of aconstituent in a molten metal bath and also to a preferredsampler-reactor for the system.

The invention is particularly useful in determining oxygen content of amolten steel bath, for example during vacuum degassing to ascertain theamount of aluminum to be added or late in a blow in the basic oxygenfurnace (BOF) to determine recovery on alloy additions. It is alsouseful late in the blow in the BOF to determine carbon levels to arriveat precise tumdown times.

U.S. Pat. No. 2,336,075 discloses two ways of analyzing for oxygen inmolten steel. Firstly, the patent discloses a bomb method in whichaluminum is placed in a cast iron bomb provided with a thin metal coverand the bomb is placed in a steel bath; the thin metal cover melts, thesteel flows into the bomb and the iron oxide in the steel converts thealuminum to alumina; the bomb is removed from the bath and the contentsanalyzed for slumina either by a turbidity method involving treatmentwith acid and measuring the turbidity of the solution or by a vacuumfusion treatment to reduce the alumina. Secondly, the patent discloses amethod comprising obtaining a sample in a spoon and freezing it asrapidly as possible by pouring it into a copper mold, breaking off aportion of from 10 to 20 grams, introducing this portion into a graphitecrucible, then heating under vacuum whereby carbon dissolved in thesteel reacts with oxygen in the steel to form carbon monoxide andcollecting evolved gases in a known volume reservoir and measuring thepressure. Each of these methods is relatively time-consuming andcomplicated.

In a method different from the above which is being utilized, a Halydipper is used to take a cylindrical sample (about 1 inch in diameterand about 3 inches long) which after solidification is transferred to alaboratory where it is allowed to cool further, out to a particularsize, polished to remove surface oxidation present due to exposure ofthe sample during transfer to the laboratory, punched, remelted in agraphite crucible whereby the carbon of the crucible reacts with oxygenin the sample to form carbon monoxide and the carbon monoxide is sweptto a gas chromatograph using helium as a carrier gas. This methodrequires about l minutes.

It is an object of the present invention to provide a method and systemwhich is significantly more rapid than the above in that it providesresults in 2 to 3 minutes or less. In determining the oxygen content ofa bath of molten steel, such rapid results offer maximum aid to theoperators and enable more precise control for example of oxygen removaland alloy additions.

This object and others will be evident from the following detaileddescription.

BRIEF DESCRIPTION OF THE DRAWING FIG. 2 is a sectional view of apreferred samplerreactor for a system in accordance with the invention.

FIG. 3 is a sectional view taken at line 33 of FIG. 2.

FIG. 4 is a sectional view taken at line 44 of FIG.

FIG. 5 is a sectional view taken at line 5-5 of FIG. 2.

DETAILED DESCRIPTION Referring to FIG. 1, reference numeral 10 denotes avessel for containing molten steel which is hereinafter referred to as aladle, and reference numeral 12 denotes a system in accord with thepresent invention useful for determining, for example, the oxygencontent of a molten steel bath in the ladle 10. The system 12 in cludesthree sampler-reactors denoted 14a, 14b and respectively. Conduit means16a contains a valve and communicates at its downstream end with aninlet into sampler-reactor 14a. Conduit means 16b contains a valve andcommunicates at its downstream end'with an inlet into sampler-reactor14b. Conduit means contains a valve and communicates at its downstreamend with an inlet into sampler-reactor 140. The conduit means 16a, 16band 160 each communicate at their upstream ends with a header 18. Theheader 18 contains a valve and communicates at its upstream end with asource of gas depicted as pressurized tank 20. A conduit 22a contains avalve and communicates at its upstream end with an outlet fromsampler-reactor 140. A conduit22b contains a valve and communicates atits upstream end with an outlet from sampler-reactor 14b. A conduit 220contains a valve and communicates at its upstream end with an outletfrom sampler-reactor 140. The conduits 22a, 22b and 22c each communicateat their downstream ends with a header 24 which in turn communicateswith a gas chromatograph 26. The chromatograph 26 is also incommunication with header 18 at a location between the valve in headerl8 and where header 18 is in communication with conduit means 16a, 16band 160. The conduits 16a, 16b, 16c, 22a, 22b and 22c are of flexiblematerial so as to be easily extended and retracted during use.Preferably, the chromatograph is positioned 15 to 30 feet from ladle 10so as to be protected from the hostile environment associated with theladle.

Referring to FIG. 2, a sampler-reactor denoted 14a (14b and 14c arestructurally the same) has an elongated cylindrical exteriorconfiguration.

The cylinder sidewall is defined by tubular member 28.-Member 28 iscomposed of refractory material such as ceramic material so as toprotect the sampler-reactor when it is inserted into molten metal asdescribed later.

Toward the forward end of the sampler-reactor is an annular tube 30. Thetube 30'has an outer diameter equal to the inner diameter of tube 28 andis coaxial therewith. Tube 30 is composed of graphite.

Forward of tube 30 is a disc-shaped element 32. The element 32 iscoaxial with tube 28 and has a diameter equal to the inner diameter oftube 28. The element 32 has an inner face 34 which toward its peripherybutts up against the forward end of tube 30. It has an outer face 36which is coplanar with the forward end of tube 28. The element 32 iscomposed of graphite. With reference to FIG. 5, the element 32'containsfour holes 38 A disc-shaped element 40 is directly rearward of tube 30.Element 40 has a diameter equal to that of the inner diameter of tube 28and is coaxial therewith. It has a forward surface 42 which toward itsperiphery butts up against the rearward end of tube 30. It has arearward surface 44. The element 40 is composed of graphite. Withreference to FIG. 4, element 40 contains a multiplicity of axiallyextending passageways 46, for example to 40 of such passageways. Thesepassageways each have a diameter sufficiently large so that gas can passtherethrough but sufficiently small so that molten metal will not passtherethrough. Preferably these passageways have diameters ranging fromabout 0.020 to about 0.040 of an inch.

The elements 30, 32 and 40 coact to provide a sample-receiving chamber48. The chamber 48 is of sub stantially cylindrical configuration. it iscoaxial with tube 28. It has a sidewall provided by the inner surface ofelement 30, a forward endwall provided by a portion of the inner face 34of member 32 and a rear endwall provided by a portion of the forwardsurface 42 of element 40. lnlets into chamber 48 are provided by holes38 and outlet means from chamber 48 is provided by passageways 46.

A cap 50 is at the forward end of the sampler-reactor. It is fitted overthe forward end of tube 28. It protects element 32 from exposure to theenvironment and prevents foreign material from entering throughpassageways 38 into chamber 48 thereby isolating chamber 48 from theatmosphere and contaminants. The cap 50 is of a thickness and composedof metal such as to melt when inserted into a molten metal bath therebyexposing holes 38 to the molten bath so that molten metal can enterchamber 48 therethrough.

A tube 51 extends starting just back of element 40. It is coaxial withtube 28 and has an outer diameter equal to the inner diameter of tube28. It has an inner diameter the same as the inner diameter of tube 30.It has a forward end which butts up against surface 44 of element 40. Ithas a rearward end which is coplanar with the rearward end of tube 28.It is composed of steel.

Within tube 51 spaced from element 40 is a discshaped element 52. Theelement 52 is coaxial with tube 28. It is composed of steel. Withreference to FIG. 3, the element 52 contains two passagewaysextendingaxially therethrough, an inlet passageway 54a and an outlet passageway54b. The passageways 54a and 54b are positionedsymmetrically withrespect to element 52.

O-ring 56 provides fluid-tight sealing engagement between element 52 andthe interior wall of tube 51.

A chamber 58 for receiving gaseous product from chamber 48.throughpassageways 46 is defined by a portion of rear surface 44 of element 40,a portion of the interior sidewall surface of element 51 and the forwardface of element 52.

Fastened into the passageway 54a is the downstream end of a tube 60.This tube is positioned axially within tube 28 and extends slightlybeyond the plane of the rearward ends of tube 28 and tube 51. Tube 60 iscomposed of steel. As previously indicated a different conduit meanscommunicates with an inlet of each sampler-reactor and the particularconduit means communicating with sampler-reactor 14a is denoted 16a. Theconduit means 16a is in the form of a carrier gas inlet pipe and suchconnects with the portion of tube 60 extending beyond the plane of theend of tube 28 whereby carrier gas may be fed into tube 60. Conduits 16band 16c are connected in similar fashion respectively withsampler-reactors 14b and 14c. 7 H u v A tube 62 is fastened at itsupstream end into the other passageway 54b and extends rearwardlytherefrom axially in relation to tube 28. It extends slightly past theplane of the rearward end of tube 28. It is composed of steel. Aspreviously indicateda different conduit communicates with the outlet ofeach samplerreactor and the particular conduit communicating with theoutlet of sampler-reactor 14a is denoted 22a. The conduit 22a is in theform of a gas outlet tube which is fastened to the end of tube 62extending beyond the plane of the face of the rearward end of tube 28 sothat gas may pass from tube 62 into tube 22a. Conduits 22b and 220 areconnected in similar fashion respectively with sampler-reactors 14b and140. The conduits 22a, 22b and 22c respectively provide in combinationwith header 24 direct communication between samplerreactors 14a, 14b andand chromatograph 26.

A disc-shaped element 64 is positioned within element 51 at its rearwardend so as to have its rear. face coplanar with the rear faces ofelements 28 and 51. It has passageways therein corresponding to thepassageways 54a and 54b of element 52 and tubes 60 and 62 extend'throughthese passageways whereby member 64 supports tubes 60 and 62 axially ofelement 28.

The operation of the above system is now described for purposes ofconvenience where ladle 10 is a degassing vessel and the temperature ofthe molten steel is in the range of temperatures normally encounteredduring degassing. The system is used to measure the concentration ofactive oxygen in the molten steel. The term active oxygen is used toinclude both free and combined oxygen except that combined with aluminumand that combined with silicon under the degassing conditions.

While three sampler-reactors have been depicted in FIG. 1, only one isused at a time. The operation is therefore described in detail withrespect to a single sampler-reactor 14a. The operation ofsamplerreactors 14b and 140 is described thereafter.

When sampler-reactor 14a is utilized the valve in conduit 18 ismaintained open as well as the valves in conduits 16a and 22a while thevalves in conduits 16b, 16c, 22b and 22c are maintained closed.

In operation, the sampler-reactor 14a is introduced into a bath ofmolten steel in ladle 10. When the forward end of the sampler-reactorenters the bath, cap 50 melts off and molten steel flows throughpassageways 38 into chamber 48 substantially filling that chamber. Amolten sample is thereby obtained in chamber 48. The amount of thesample is predetermined by the volume of chamber 48.

As the molten steel enters chamber 48, the graphite wall structure ofelements 30, 32 and 40 provides a source of carbon, that is acarbonaceous environment, so that the carbon level in the sample buildsup to, for example 0.5 percent so that the equilibrium level of activeoxygen therein is very low, e.g. less than 15 ppm. The active oxygen inexcess of this equilibrium level reacts with carbon in the carbonaceousenvironment to form carbon monoxide prior to the freezing of the steel.

Thus chamber 48 functions as a zone for obtaining and isolating a moltensample; as a zone where reactant and in particular carbon in thecarbonaceous environment provided by the wall structure of the chamberbuilds up in the molten sample to lower the equilibrium level of activeoxygen in the sample to a point where said equilibrium level is lowenough so that it can be ignored or readily corrected for; and as areaction zone where the sample still in molten state and in particularthe active oxygen in the sample in excess of the newly provided lowerequilibrium level is reacted to form the gaseous product carbon monoxidewhich is stoichiometrically related to the active oxygen constituentbeing analyzed for.

Carrier gas, preferably helium or argon, from pressurized cylinderpasses through header 18 into inlet conduit 16a, then into tube 60 andthen through passageway 54a into the chamber 58.

The carbon monoxide as it is formed flows from chamber 48 throughpassageways 46 of element into chamber 58. The carrier gas enteringchamber 58 provides a driving force for removing the carbon monoxidedirectly, that is without delay, to chromatograph 26. In particular, thecarbon monoxide is swept from that chamber and thereby sweeps the carbonmonoxide from chamber 58 through tube 62 into outlet conduit 22a.

The gas in conduit 22a passes to header 24 and into the analytical zonedefined by chromatograph 26 whereby a reading on the level of carbonmonoxide is provided. The communication of header 18 with thechromatograph 26 provides a reference whereby any effect of thecomposition of the carrier gas on the reading obtained is eliminated.The reading obtained is in the form of a peak on a graph. This data istranslated into concentration of oxygen by comparison to standardgraphs. The standard graphs are obtained for a particular system byutilizing the system to obtain a graph and simultaneously obtaining adifferent sample which is conventionally analyzed; by doing this anumber of times a set of graphs are obtained with each particular graphcorresponding to a particular concentration.

In the above, the chamber 58 functions as a removal zone, that is as azone whereby the formed, gaseous product is removed to an analyticalzone, namely the chromatograph.

The construction of sampler-reactor 14a is such that i the molten metalentering chamber 48 is allowed to remain molten for sufficient time (20to 40 seconds) that substantially all of the active oxygen in the sampleis driven out therefrom and converted into carbon monoxide and so thatat the time when or soon after this has occurred the sample solidifiesso as to seal the forward end of chamber 48 so that extraneousconstituents do not interfere with the accuracy of the analyticalresults.

blow in the BOF of providing data whereby alloy recoveries can beaccurately determined; in other words, whereby it can be determinedrapidly how much of an alloying agent should be added to obtain aparticular level in the final product.

With the apparatus depicted in FIG. 1 a second analysis is ready to beobtained on completion of the-first analysis by simply closing valves16a and 22a and opening valves 16b and 22b and inserting sampler-reactor14b into the molten metal.

With corresponding manipulation of the valves, a

third analysis can be taken utilizing sampler-reactor 14c.

Thus, with the depicted embodiment (FIG. 1) three successive analysescan be taken. Inasmuch each analysis takes three minutes or less, thethree successive analyses can be obtained in less than ten minutes whichis the time period which has heretofore been necessary in practice toobtain a single analytical result.

A detailed description of the most preferred embodi-' ment ofsampler-reactor follows. The sampler-reactor is that depicted in FIG. 2.The elements 30, 32 and 40 are of spectrographically pure graphite. Thediameter of chamber 48 is /2 inch. The length of chamber 48 is %inch.The wall thickness of element 30 is /8 inch. The axial dimension ofelement 32 is inch. Each of the holes 38 in element 32 has a diameter of3/32 of an inch. The axial dimension of member 40 is A inch. Member 40contains 30 closely spaced passageways each 0.030 of an inch indiameter. Chamber 58 has an axial dimension of 1 inch and a diameter ofk inch. Element 51 has a thickness of /a inch and an axial dimension of4 feet. It is made of steel. Each of the passageways 54a and 54b ofelement 52 has a diameter of A: inch. Element 52 is made of steel.O-ring 56 is made of Viton. Each of the tubes 60 and 62 are steel pipeshaving outside diameters of Va inch. Element 64 is made of steel.Element 28 is A inch thick and made of ceramic material. Cap 50 is madeof 18 gage steel. The samplerreactor so constructed is utilized todetermine the active oxygen content in a ladle of molten steel duringdegassing. The temperature of the molten steel is about 2,900" F. Theforward end of the sampler-reactor is inserted into the steel bath. Whenthe sampler-reactor is inserted, cap 50 melts off and molten steelenters substantially filling chamber 48. The weight of the sampleobtained is approximately 40 grams. The molten steel enters the chamber48 through the passageways 38. As it so enters and contacts thecarbonaceous environment in the form of the graphite members 30, 32 and40, the carbon level in the sample builds up to the point where itcontains about 0.5 percent carbon and the equilibrium level of activeoxygen in the sample is about 5 p.p.m. by weight. The oxygen driven outfrom the sample due to the equilibrium shift reacts with thecarbonaceous environment in the form of the walls 30,

32 and 40 and is converted to carbon monoxide which is passed throughpassageways 46 into chamber 58. The sample remains molten for about 30seconds after the sampler is inserted into the bath, whereupon thesample solidifies to the extent that passageways 38 are blocked. Astream of helium gas is passed from tank 20 through header 18 andconduit 16a into the samplerreactor and passes through tube 60,passageway 54a and element 52 into chamber 58 wherein it picks up thecarbon monoxide in chamber 58 and sweeps it out of chamber 58 throughtube 62. The gas leaving chamber 58 after passing through tube 62 passesinto tube 22a and then into header 24 and then is directed to the gaschromatograph 26. The distance of the chromatograph from the ladle isabout feet, and this is a distance sufficiently far as to providesecurity from the hostile environment of the ladle. The gaschromatograph provides a peak reading which is translated by referenceto standard graphs as previously described into active oxygen content,for example 150 ppm. active oxygen indicating to the operator the extentof degassing. The analytical result is obtained in less than 2 minutes.

All percentages and parts herein are by weight unless otherwise stated.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof.

For example, the above system can be utilized to obtain a reading on thelevel of carbon in a molten steel bath. This can be done because activeoxygen and carbon are in equilibrium in a molten steel bath. Thus, withequilibrium data at the particular temperature concerned, the reading onthe gas chromatograph can be converted into a determination of carboncontent. This analysis for carbon level is useful late in the blow inthe BOP to arrive at precise turndown times.

Furthermore, the system can be utilized to determine the concentrationof constituents in molten metal baths other than molten steel baths, forexample the system is useful in determining the oxygen content in a bathof molten copper. Such reading is important because the oxygen contentin copper is controlled to adjust workability. Oxygen is added bypoling, i.e., by inserting green poles into a molten copper bath. Theuse of the above described system is helpful in detennining the amountof poling to obtain a given degree of workability.

Moreover, different sample-receiving chambers from the one specificallydescribed before can be utilized so long as the chamber contains asuitable inlet and outlet and so long as a very large excess of reactantis provided. The element 40 can, for example, be porous instead ofcontaining a definite number of distinct passageways; where the reactantis carbon, element 40 can be composed of porous graphite. The excess ofreactant can be for example on the order of 100 times stoichiometric ormore.

Moreover, a control integrator can be utilized to electronically convertthe chromatographic output to a numerical readout or the output from thechromatograph might be fed to a computer input.

Moreover, other types of gas analyzers may be utilized instead of gaschromatographs as long as they can quantitatively analyze for thegaseous product; for example an infrared analyzer can be utilized.

8 Moreover, a system can be provided with only a single samplerreactoror any number of sampler-reactors.

Furthermore, the sampler-reactor can carry a temperature sensing deviceso that a temperature reading is obtained at the same time aconcentration determination is obtained.

In view of the variations that are readily understood to come within thelimits of the invention, such limits are defined by the scope of theappended claims.

What is claimed is:

1. Method of determining the concentration of a constituent in a moltenmetal bath comprising the steps of obtaining a molten sample from thebath in a reaction zone,

reacting said sample still in molten state in said zone to form gaseousproduct related to said constituent,

removing said product directly to an analytical zone,

and quantitatively analyzing for said product.

2. Method as recited in claim 1 for determining the concentration ofactive oxygen in a bath of molten steel.

3. Method as recited in claim 2 wherein the reaction zone comprises acarbonaceous environment whereby the carbon level in the molten samplebuilds up to the point where the equilibrium level of active oxygen inthe sample is less than 15 ppm.

4. Method as recited in claim 3 wherein said step of reacting saidsample comprises reacting the active oxygen in excess of saidequilibrium level with carbon in said carbonaceous environment and thegaseous product formed is carbon monoxide.

5. Method as recited in claim 4 comprising allowing said sample toremain molten for 20 to 40 seconds.

6. Method as recited in claim 4 wherein the step of removing the gaseousproduct to an analytical zone comprises passing gaseous product to aremoval zone, introducing a stream of carrier gas analytically distinctfrom the product gas into the removal zone and removing a stream of gascontaining product gas from the removal zone utilizing the carrier gasstream as the driving force.

7. Method as recited in claim 6 wherein the step of analyzing comprisesgas chromatographic analysis.

8. Method as recited in claim 7 wherein the carrier gas has a molecularweight substantially different from that of the gaseous-product.

9. Method as recited in claim 8 wherein the carrier gas is selected fromthe group consisting of helium and argon.

10. System for determining the concentration of a constituent in amolten metal bath comprising a. sampler-reactor including i. means toisolate a sample of molten metal from said bath, I

ii. a source of reagent in means (i) which reacts to form gaseousproduct related tosaid constituent,

iii. means to remove gaseous product including carrier gas inlet meansand gas outlet means; b. first conduit means communicating with saidinlet means; c. a source of carrier gas communicating with said firstconduit means; and

i d. means directly communicating with said gas outlet means forquantitatively analyzing gaseous prod- UCI.

11. System as recited in claim 10 wherein the source of reagent is asource of carbon.

12. System as recited in claim 11 wherein the carbon is in the form ofspectrographically pure graphite.

13. System as recited in claim 10 wherein the source of carrier gas is asource of helium.

14. System as recited in claim 10 wherein said means (e) is a gaschromatograph.

l5. Sampler-reactor comprising a. means defining a chamber for receivinga sample from a bath of molten metal comprising wall means composed of asource of reagent which reacts with a constituent of the sample to formgaseous product, said chamber means having a forward end and a rearwardend;

b. means defining said forward end including molten metal inlet means;

c. means defining said rearward end including outlet means for gaseousproduct;

d. means defining a chamber for receiving gaseous product from theoutlet means of element (c) and including gaseous product inletmeansjcarrier gas inlet means and gas outlet means.

16. Samplerreactor as recited in claim 15 wherein the rearward end ofthe sampler-receiving chamber is a wall common to the gaseousproduct-receiving chamber.

17. Sampler-reactor as recited in claim 16 wherein said wall contains amultiplicity of 'orificies providing the outlet means of element (c) andcommunication between the sample-receiving chamber and the gaseousproduct-receiving chamber.

18. Sampler-reactor as recited in claim 17 wherein the forward end ofthe sample-receiving chamber is a wall containing orifice meansproviding the molten metal inlet means of element (b).

19. Sampler-reactor as recited in claim 18 wherein the wall at theforward end of the sample-receiving chamber has its exterior protectedby a cap which melts off when inserted into a molten metal bath.

20. Sampler-reactor as recited in claim 18 wherein the sample-receivingchamber is substantially cylindrical comprising sidewall in addition tothe walls at the forward and rearward ends and said sidewall and forwardand rearward walls are composed of carbon.

21. Sampler-reactor as recited in .claim .20 wherein the carbon is inthe form of spectrographically pure graphite.

22. Sampler-reactor as recited in claim 18 wherein the gaseousproduct-receiving chamber is substantially cylindrical having a wall atits rearward end containing orifice means providing the carrier gasinlet means of element (d) and other orifice means providing the gasoutlet means of element (d).

23. Sampler-reactor as recited in claim 15 additionally comprising afirst conduit means communicating with the carrier gas inlet means ofelement (d) and a second conduit means communicating with the gas outletmeans of element (d) 24. Sampler-reactor as recited in claim 15 havingan elongated cylindrical exterior configuration with the cylindersidewall comprising refractory material and a forward end protected byamelt-off cap.

25. System for determining the concentration of a constituent in amolten metal bath comprising a. sampler-reactor including i. meansdefining a chamber for receiving a sample from a bath of molten metalcomprising wall means composed of a source of reagent which reacts witha constituent of the sample to form gaseous product, said chamber havinga forward end and a rearward end;

ii. wall means defining said forward end, containing orifice meansproviding molten metal inlet means;

iii. wall means defining said rearward end containing means providingoutlet means for gaseous product from means (i);

iv. means defining a chamber for receiving gaseous product from theoutlet means of means (iii) and including gaseous product inlet means,carrier gas inlet means and gas outlet means;

b. first conduit means communicating with the carrier gas inlet means ofmeans (iv);

e. a source of carrier gas communicating with said first conduit means;

(1. second conduit means communicating with the gas outlet means ofmeans (iv); and

e. means communicating with said second conduit means for quantitativelyanalyzing gaseous prod- UCt.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,820,380 Dated June 28, 1974 1 Gerald G. Miller and Rox L. ZickefooseIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

At column 1, line 25, "slumina" should be changed to -alumina.

At column 9, lines 1-3, "d. means directly communicating with said gasoutlet means for quantitatively analyzing gaseous product. should bechanged to (d) means providing direct communication between said gasoutlet means and means e) (e) means for quantitatively analyzing gaseousproduct- Signed and sealed this 8th day of October 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents 'JRM PC2-1050 (10-69) USCOMM-DC 60376-969 fl U.$. GOVERNMENTPRINTING OFFICE I969 0-358-331

1. Method of determining the concentration of a constituent in a moltenmetal bath comprising the steps of obtaining a molten sample from thebath in a reaction zone, reacting said sample still in molten state insaid zone to form gaseous product related to said constituent, removingsaid product directly to an analytical zone, and quantitativelyanalyzing for said product.
 2. Method as recited in claim 1 fordetermining the concentration of active oxygen in a bath of moltensteel.
 3. Method as recited in claim 2 wherein the reaction zonecomprises a carbonaceous environment whereby the carbon level in themolten sample builds up to the point where the equilibrium level ofactive oxygen in the sample is less than 15 p.p.m.
 4. Method as recitedin claim 3 wherein said step of reacting said sample comprises reactingthe active oxygen in excess of said equilibrium level with carbon insaid carbonaceous environment and the gaseous product formed is carbonmonoxide.
 5. Method as recited in claim 4 comprising allowing saidsample to remain molten for 20 to 40 seconds.
 6. Method as recited inclaim 4 wherein the step of removing the gaseous product to ananalytical zone comprises passing gaseous product to a removal zone,introducing a stream of carrier gas analytically distinct from theproduct gas into the removal zone and removing a stream of gascontaining product gas from the removal zone utilizing the carrier gasstream as the driving force.
 7. Method as recited in claim 6 wherein thestep of analyzing comprises gas chromatographic analysis.
 8. Method asrecited in claim 7 wherein the carrier gas has a molecular weightsubstantially different from that of the gaseous product.
 9. Method asrecited in claim 8 wherein the carrier gas is selected from the groupconsisting of helium and argon.
 10. System for determining theconcentration of a constituent in a molten metal bath comprising a.sampler-reactor including i. means to isolate a sample of molten metalfrom said bath, ii. a source of reagent in means (i) which reacts toform gaseous product related to said constituent, iii. means to removegaseous product including carrier gas inlet means and gas outlet means;b. first conduit means communicating with saId inlet means; c. a sourceof carrier gas communicating with said first conduit means; and d. meansdirectly communicating with said gas outlet means for quantitativelyanalyzing gaseous product.
 11. System as recited in claim 10 wherein thesource of reagent is a source of carbon.
 12. System as recited in claim11 wherein the carbon is in the form of spectrographically puregraphite.
 13. System as recited in claim 10 wherein the source ofcarrier gas is a source of helium.
 14. System as recited in claim 10wherein said means (e) is a gas chromatograph.
 15. Sampler-reactorcomprising a. means defining a chamber for receiving a sample from abath of molten metal comprising wall means composed of a source ofreagent which reacts with a constituent of the sample to form gaseousproduct, said chamber means having a forward end and a rearward end; b.means defining said forward end including molten metal inlet means; c.means defining said rearward end including outlet means for gaseousproduct; d. means defining a chamber for receiving gaseous product fromthe outlet means of element (c) and including gaseous product inletmeans, carrier gas inlet means and gas outlet means.
 16. Sampler-reactoras recited in claim 15 wherein the rearward end of the sampler-receivingchamber is a wall common to the gaseous product-receiving chamber. 17.Sampler-reactor as recited in claim 16 wherein said wall contains amultiplicity of orificies providing the outlet means of element (c) andcommunication between the sample-receiving chamber and the gaseousproduct-receiving chamber.
 18. Sampler-reactor as recited in claim 17wherein the forward end of the sample-receiving chamber is a wallcontaining orifice means providing the molten metal inlet means ofelement (b).
 19. Sampler-reactor as recited in claim 18 wherein the wallat the forward end of the sample-receiving chamber has its exteriorprotected by a cap which melts off when inserted into a molten metalbath.
 20. Sampler-reactor as recited in claim 18 wherein thesample-receiving chamber is substantially cylindrical comprisingsidewall in addition to the walls at the forward and rearward ends andsaid sidewall and forward and rearward walls are composed of carbon. 21.Sampler-reactor as recited in claim 20 wherein the carbon is in the formof spectrographically pure graphite.
 22. Sampler-reactor as recited inclaim 18 wherein the gaseous product-receiving chamber is substantiallycylindrical having a wall at its rearward end containing orifice meansproviding the carrier gas inlet means of element (d) and other orificemeans providing the gas outlet means of element (d).
 23. Sampler-reactoras recited in claim 15 additionally comprising a first conduit meanscommunicating with the carrier gas inlet means of element (d) and asecond conduit means communicating with the gas outlet means of element(d)
 24. Sampler-reactor as recited in claim 15 having an elongatedcylindrical exterior configuration with the cylinder sidewall comprisingrefractory material and a forward end protected by a melt-off cap. 25.System for determining the concentration of a constituent in a moltenmetal bath comprising a. sampler-reactor including i. means defining achamber for receiving a sample from a bath of molten metal comprisingwall means composed of a source of reagent which reacts with aconstituent of the sample to form gaseous product, said chamber having aforward end and a rearward end; ii. wall means defining said forwardend, containing orifice means providing molten metal inlet means; iii.wall means defining said rearward end containing means providing outletmeans for gaseous product from means (i); iv. means defining a chamberfor receiving gaseous product from the outlet means of means (iii) andincluding gaseous product inlet means, carrier gas inlet means and gasoutlet means; b. first conduit means communicating with the carrier gasinleT means of means (iv); c. a source of carrier gas communicating withsaid first conduit means; d. second conduit means communicating with thegas outlet means of means (iv); and e. means communicating with saidsecond conduit means for quantitatively analyzing gaseous product.